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1 TTTTTTTTTTT Patented Aspr. 3,1883.

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UNITED. STATES PATENT OFFICE.

THOMAS HOOKER, OF SYRAOUSE, NEW YORK.

TWIST-DRILL.

SPECIFICATION forming part of Letters Patent No. 274,943, dated April 3, 1883.

Application tiled May 3, 1882.

` To all whom it may concern Be it known that I, THOMAS HOOKER, of Syracuse, in the county ot' Onondaga, in the State4 of New York, have invented new and `usel'ul Improvements in Twist-Drills, of which the following. taken in connection with the accompanying drawings, is a full, clear, and eX- act description.

This inventionV relates to an improved process of soliditying and nishing the cuttingedges of twist-drills; and it consists in forming the drill with a diametric enlargement along the cutting-edges thereof, and subsequently compressing said edges to the requisite diameter ofthe drill, substantially as hereinafter more fully described, and sct forth in the claim.

To enable others to fully comprehend my invention, I have shown in the annexed drawings one of the means by which the object may be obtained.

. Figure l represents a transverse section ot' a set of rollers arranged to receive between them the drill to be compacted at its cuttingedges; and Fig. 2 is a transverse section of a twist-drill, illustrating its form before it is subjected to the compression of its cuttingedges.

The drill is brought to the approximate size and form by any of the usual methods, but leaving the forward or cutting edges, a a, of the spiral or twistedribs b b projecting somewhat over the'reqniste diameter ot' the drill,l

as illustrated in Fig. 2 of the drawings. The drill in this condition issubjected to circumferential compression by two parallel horizontal revolving rollers,l R R, which are arranged at a slightly-less distance apart than the diameterof the nished drill, the drill to be treated (No model.)

rially improves the general finish ot' the drill.

The process of compressing the cutting-edges can be applied to the drill either in a heated or cold condition, the latter being generally preferred.

I do not limit myself tothe use of rollers,as it is evident the same result may be obtained by dies or other mechanical means.

Havingdescribed my invention, what I claim as new, and desire to secure by Letters Patent, 1s-

The within-described process ot' solidifying and iinishing the cutting-ed ges off-twist-drills, the same consisting in forming the drill with a diametric enlargement along the cuttingedges thereof, and subsequently compressiu g said edges to the requisite diameter of the drill, substantially as specified.

In tcstimon y whereof I have hereunto signed my name and affixed my seal, in the presence of two attesting witnesses, at Syracuse, in the county of' Onondaga, in the State ot' New York, this 28th day of April, 1882.

THOMAS HOOKER. [L. SJ 

